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1.
Rapid catalytic thermal conversion of Physic nut (Jatropha curcas) residues for upgrading the released vapors was performed using analytical pyrolyzer-gas chromatography/mass spectrometry at 873 K. Conditioning of the evolved vapor product is required since the main vapor products formed without catalysts typically contained around 60% fatty acids, while the total hydrocarbon yields were only 12%. Catalysts tested were alumina (Al2O3) alone and modified by 5 wt% impregnation with various transition metal salts and then calcined to metal oxides. A significant decrease in the proportion of oxygenated compounds (including acids) from 73% without a catalyst to less than 10% with, and an increased conversion to hydrocarbons of more than 70% was obtained with the metal/Al2O3 catalysts at a Jatropha:catalyst (J:C) ratio of 1:10. The product selectivity was greatly increased as the J:C ratio was increased from 1:1 to 1:10. The total hydrocarbon selectivity of the metal/Al2O3 catalysts was increased in the order of Pd > Ni > Ce > Ru > La > none > Co > Mo, with the highest proportion of total hydrocarbons obtained being 75%. In addition, only a low yield (<2%) of polycyclic aromatic hydrocarbons was obtained from the conversion of Jatropha curcas residues. However, these catalysts adversely promoted N-containing compounds, suggesting that a further denitrogenation process is necessary. Nevertheless, the overall performance of these transition metal/Al2O3 catalysts is acceptable and they can be considered as good candidates for bio-oil upgrading.  相似文献   

2.
《能源学会志》2020,93(2):605-613
The Fe-, Co-, Cu-loaded HZSM-5 zeolites were prepared via impregnation method. The upgrading by catalyst on biomass pyrolysis vapors was conducted over modified zeolites to investigate their catalytic upgrading performance and anti-coking performance. The Brønsted acid sites amount on Cu-,Co-loaded HZSM-5 decreased sharply, while that of Lewis both increased. The yield of liquid fraction and refined bio-oil over metal loaded ZSM-5 catalysts decreased, while that of char almost kept constant. The physical property of refined bio-oil was promoted in terms of pH value, dynamic viscosity and higher heating value (HHV). FT-IR analysis revealed that the chemical structure of refined bio-oil obtained over Fe-, Co-, Cu-loaded HZSM-5 zeolites was highly similar. The yield of monocyclic aromatic and aliphatic hydrocarbon over Fe-,Co-loaded HZSM-5 were boosted by around 2.5 times compared with original ZSM-5 zeolites. Data analysis revealed that Cu/HZSM-5 presented the worst deoxygenation ability. The anti-coking capability of Fe/HZSM-5 was obviously better, i.e., the coke content showed an approximate decrease of 38%. Thus, this study provided an efficient Fe/HZSM-5 catalysts for preparation of bio-oil derived from catalytic upgrading of biomass pyrolysis vapor.  相似文献   

3.
Metal based-zeolite catalysts were successfully prepared by two different methods including ion-exchange and wet impregnation. HZSM-5 synthesized by hydrothermal method at 160 °C was used as a support for loading metals including Co, Ni, Mo, Ga and Pd. The metal/HZSM-5 had surface area and pore size of 530–677 m2/g and 22.9-26.0 Å. Non- and catalytic fast pyrolysis of Jatropha residues using metal/HZSM-5 were studied using an analytical pyrolysis-GC/MS at 500 °C. Non-catalytic pyrolysis vapors contained primarily high levels acid (50.7%), N-containing compounds (20.3%), other oxygenated compounds including ketones, alcohols, esters, ethers, phenols and sugars (25.0%), while generated small amount of aromatic and aliphatic hydrocarbons of 3.0% and 1.0%. The addition of synthesized metal/HZSM-5 improved the aromatic selectivity up to 91–97% and decreased the undesirable oxygenated (0.6–4.0%) and N-containing compounds (1.8–4.6%). The aromatic selectivity produced by metal-ion exchanged catalysts was slightly higher than that produced by impregnated ones. At high catalyst content (biomass to catalyst ratio of 1:10), Mo/HZSM-5 showed the highest aromatic selectivity of 97% for ion-exchanged catalysts and Ga/HZSM-5 revealed the highest aromatics of 95% for impregnated catalysts. The formation of aromatic compounds could be beneficial to improve calorific values of bio-oils. The presence of metal/HZSM-5 from both preparation methods greatly enhanced MAHs selectivity including benzene, toluene, and xylene (BTX), while substantially reduced unfavorable PAHs such as napthalenes.  相似文献   

4.
The present study is aimed to investigate the upgrading of beech sawdust pyrolysis bio-oil through catalytic cracking of its vapors over Fe-modified ZSM-5 zeolite in a fixed bed tubular reactor. The zeolite supported iron catalyst was successfully prepared with varying metal loading ratios (1, 5, 10 wt%) via dry impregnation method and further characterized by BET, XRD, and SEM-EDX techniques. TG/FT-IR/MS analysis was used for the detection of biomass thermal degradation. Product yields of non-catalytic and catalytic pyrolysis experiments were determined and the obtained results show that bio-oil yields decreased in the presence of catalysts. Besides, the bio-oil composition is characterized by GC/MS. It was indicated that the entity of the ZSM-5 and Fe/ZSM-5 catalyst reveal a significant enhancement quality of the pyrolysis products in comparison with non-catalytic experiment. The catalyst increased oxygen removal from the organic phase of bio-oil and further developed the production of desirable products such as phenolics and aromatic compounds.  相似文献   

5.
In this study, pyrolysis of tomato waste has been performed in fixed bed tubular reactor at 500 °C, both in absence and presence of Cu/Al2O3 catalyst. The influences of heating rate, catalyst preparation method and catalyst loading on bio-oil yields and properties were examined. According to pyrolysis experiments, the highest bio-oil yield was obtained as 30.31% with a heating rate of 100 °C/min, 5% Cu/Al2O3 catalyst loading ratio and co-precipitation method. Results showed that the catalysts have strong positive effect on bio-oil yields. Bio-oil quality obtained from fast catalytic pyrolysis was more favorable than that obtained from non-catalytic and slow catalytic pyrolysis.  相似文献   

6.
Despite remarkable progress in catalytic fast pyrolysis, bio-oil production is far from commercialization because of multi-scale challenges, and major constraints lie with catalysts. This review aims to introduce major constraints of acid catalysts and simultaneously to find out possible solutions for the production of fuel-grade bio-oil in biomass catalytic fast pyrolysis. The catalytic activities of several materials which act as acid catalysts and the impacts of Bronsted and Lewis acid site on the formation of aromatic hydrocarbons are discussed. Considering the complexity of catalytic fast pyrolysis of biomass with acid catalysts, in-depth understandings of cracking, deoxygenation, carbon-carbon coupling, and aromatization for both in-situ and ex-situ configurations are emphasized. The limitation of diffusion along with coke formation, active site poisoning, thermal/hydrothermal deactivation, sintering, and low aromatics in bio-oil are process complexities with solid acid catalysts. The economic viability of large-scale bio-oil production demands progress in catalyst modification or/and developing new catalysts. The potential of different catalyst modification strategies for an adequate amount of acid sites and pore size confinement is discussed. By critically evaluating the challenges and potential of catalyst modification techniques, multi-functional catalysts may be an effective approach for selective conversion of biomass to bio-oil and chemicals through catalytic fast pyrolysis. This review offers a scientific reference for the research and development of catalytic fast pyrolysis of biomass.  相似文献   

7.
This study investigated three different types of catalysts: Ni/HMS-ZSM5, Fe/HMS-ZSM5, and Ce/HMS-ZSM5 in the thermochemical decomposition of green microalgae Spirulina (Arthrospira) plantensis. First, non-catalytic pyrolysis tests were conducted in a temperature ranges of 400–700 °C in a dual-bed pyrolysis reactor. The optimum temperature for maximized liquid yield was determined as 500 °C. Then, the influence of acid washing on bio-products upgrading was studied at the optimum temperature. Compared to the product yields from the pyrolysis of raw spirulina, a higher bio-oil yield (from 34.488 to 37.778 %wt.) and a lower bio-char yield (from 37 to 35 %wt.) were observed for pretreated spirulina, indicating that pretreatment promoted the formation of bio-oil, while it inhibited the formation of biochar from biomass pyrolysis. Finally, catalytic pyrolysis experiments of pretreated-spirulina resulted that Fe as an active phase in catalyst exhibited excellent catalytic activity, toward producing hydrocarbons and the highest hydrogen yield (3.81 mmol/gr spirulina).  相似文献   

8.
The main objective of the present work is to investigate the influence of nickel to cerium ratio on hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) towards the catalytic upgrading of pine derived oxygenated pyrolysis vapours into aromatic hydrocarbon and phenol in pyrolysis oil via ex-situ fixed bed reactor. The presence of CeO2 could change electron density of Ni, promote the reduction of Ni species, accelerate the transfer of carbon species, and suppress the production of carbon deposits (17.53%–25.11%) compared with the parent HZSM-5 catalyst (28.95%); it also improved the hydrodeoxygenation ability of all xNiyCe/HZSM-5(nickel and cerium bimetal modified HZSM-5) catalysts, resulting increases in noncondensable gas content (from 31.46% to 52.99%–65.53%). Ni to Ce ratio of 1:1 and 1:2 produced highest aromatic hydrocarbon (32.14%) and phenols (55.51%) relative peak areas. The acid center of HZSM-5 and the metal acid center of the Ni:Ce = 1:1 catalyst obviously fine-tuned the formation of coke; and promoted hydrocarbon production. Moreover, high Ni content promoted alkylation of benzene at C6–C9 and increased C10+ PAHs relative peak area; high Ce content promoted the formation of olefin and Increasing the cleavage of C–O bonds and promoted hydrogenation or dehydrogenation, reduced polycyclic aromatic hydrocarbons and coke yield, and increased phenols and alkylphenols selectivity.  相似文献   

9.
In this study, sawdust was selected as the raw material for biomass pyrolysis to obtain organic products. The catalyst was modified with two elements (Fe and Zn). Through analysis of the catalytic products, we attempted to identify a pyrolysis catalyst that can improve the yield of aromatic hydrocarbon products. ZSM-5, modified with Fe and Zn, was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) measurements. Tube furnace and flash pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) were used to comprehensively investigate the characteristics of the products of biomass pyrolysis. The highest yield of phenols was obtained using the Fe-modified ZSM-5 catalyst, which was 18.30% higher than the yield obtained by the pure ZSM-5 catalyst. The lowest yield of acid products was obtained by single-metal-supported catalytic pyrolysis with Fe or Zn, which was 50.66% lower than the yield obtained by direct pyrolysis. During the pyrolysis of biomass using metal-modified catalysts, the production of aromatic hydrocarbons was greatly improved. Among them, compared with direct pyrolysis, the Fe-Zn co-modified ZSM-5 catalyst exhibited the weakest promotion of aromatic hydrocarbon formation, but there was still a 68.50% improvement. Although the co-modified catalyst did not show absolute advantages under the conditions used for this experiment, the improvements in the production of aromatics and phenolic products also showed its potential for improving bio-oil products. Under the action of Fe-modified catalysts, the most abundant components in the gas product were CO and CO2, which reached levels as high as 53.45% and 15.34%, respectively, showing strong deoxidation capabilities. Therefore, Fe-modified ZSM-5 catalysts were found to better promote the formation of aromatic hydrocarbon products of biomass pyrolysis.  相似文献   

10.
This study investigated the catalytic behavior of two different types of materials: (i) algal biochar and (ii) 15 wt% Ni impregnated on SBA-15 support (Ni/SBA-15), in the thermochemical decomposition of Venice lagoon brown marine algae (Sargassum). First, non-catalytic pyrolysis tests were conducted in a temperature range of 400–800 °C in a dual-bed slow pyrolysis reactor. The optimum temperature for maximized liquid yield was at the temperature of 700 °C. Biochar catalyst exhibited excellent catalytic activity toward producing aromatic compounds via Diels-Alder-type reactions. However, Ni/SBA-15, because of interconnected pores provided easy passage for reactant and product during the catalytic pyrolysis process and resulted in an improvement in total gas yield (25.87 mmol/g Sargassum) and hydrogen-rich gas production (8.54 mmol/g Sargassum). The catalytic performances of both biochar and Ni/SBA-15 catalysts were compared to biochar-based catalysts derived from red and green macroalgae. High specific surface area, large pore volume, highly ordered pore structure, and narrow pore size distribution make SBA-15 a promising catalyst support in pyrolysis of biomass.  相似文献   

11.
采用热裂解−气质联用(Py-GC/MS)技术研究Chaetoceros sp. 硅藻粉末的催化热解特性。以HZSM-5为催化剂,考察了不同Si/Al比的HZSM-5催化剂对硅藻热解产物的影响,并考察了催化剂的使用量、热解升温速率、热解反应时间对产物的影响。结果表明:未加催化剂时,硅藻热解产物以脂肪酸为主,含量为50.05%,苯系物含量仅为0.87%;加入HZSM-5催化剂后,硅藻热解产物中脂肪酸含量减少,芳香类化合物显著增加。热解实验结果发现,Si/Al比为38、硅藻和HZSM-5比例为1∶9、热解速率10 000℃/s、热解时间为10 s时,能得到较理想的热解产品,其中苯系物产率可达57.76%,脂肪酸含量为2.63%。这说明HZSM-5(38)具有较好的脱氧和芳构化功能,有利于硅藻催化热解生成高品质的生物油产品。  相似文献   

12.
HZSM-5 with high surface area of 625 m2/g was successfully synthesized by hydrothermal method at 160 °C for 72 h. The metal promoted on HZSM-5 catalyst was prepared by liquid ion exchange method. From XRD results, the addition of metals such as Co and Ni did not change the HZSM-5 structure. The metal/HZSM-5 showed lower crystallinity and surface area than the parent HZSM-5 because of the metal dispersion on the HZSM-5 surface. The metal contents of Co/HZSM-5 and Ni/HZSM-5 detected by EDX were less than 1 wt%. Catalytic fast pyrolysis of Jatropha waste using HZSM-5 and metals/HZSM-5 was investigated in terms of biomass to catalyst ratios (1:0, 1:1, 1:5 and 1:10) and types of metals (Co and Ni). From the results, it can be concluded that both biomass to catalyst ratios and the presence of metals had an effect on the increase in aromatic hydrocarbons yields as well as the decrease in the oxygenated and N-containing compounds. Both Co/HZSM-5 and Ni/HZSM-5 promoted the production of aliphatic compounds. Additionally, the PAHs compounds such as napthalenes and indenes, which caused the formation of coke, could be inhibited by metal/HZSM-5, particularly, Ni/HZSM-5. Among catalysts, Ni/HZSM-5 showed the highest hydrocarbon yield of 97.55% with N-containing compounds remained only 1.78%. The formation of hydrocarbon compounds increased the heating values of bio-oils while the elimination of the undesirable oxygenated compounds such as acids and ketones could alleviate problem regarding acidity and instability in bio oils.  相似文献   

13.
Through systematical experiments, a comparative study was conducted concerning several graphene-supported noble metal catalysts for dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). It was found that the catalytic activity of the prepared graphene-supported noble metal catalysts was following the order of Pd > Pt > Rh > Ru > Au for the dehydrogenation process. Pd supported on reduced graphene oxide (rGO) prepared by one-pot in situ synthesis has much more excellent catalytic performance than other kinds of catalysts investigated for comparison, simultaneously the using amount of noble metals can obviously be decreased. To be specific, at 453 K, the final dehydrogenation product catalyzed by the novel catalyst of Pd/rGO is N-ethylcarbazole (NEC) and the process selectivity was increased from 44.77% (commercial Pd/Al2O3) to 97.65%, as well as the dehydrogenation ratio reached 99.14%. In addition, the novel catalyst is also superior to other reported catalysts in terms of dehydrogenation performance of 12H-NEC. Its dehydrogenation activity at 443 and 433 K of Pd/rGO was tested and the catalytic performance keeps stable at the two temperatures. Based on the experimental data, kinetic calculation was carried out and some fundamental parameters regarding reaction kinetics was obtained.  相似文献   

14.
The aim of this study was to investigate the behavior of two distinct microalgae species during solar catalytic pyrolysis and the influence of their chemical composition and the process variables (biomass charge, reaction time, and catalyst percentage) on the product yields and bio-oil composition. For this purpose, solar catalytic pyrolysis of Spirulina platensis and Chlamydomonas reinhardtii was performed using hydrotalcite-derived mixed oxides as the catalyst. To gain more insight into the effect of composition on pyrolysis behavior, the biomasses were analyzed using various analytical techniques. The results indicated that a high percentage of catalyst (47.1%) culminated in liquid yields of 42.48% and 21.31% for Chlamydomonas pyrolysis and Spirulina pyrolysis, respectively. Additionally, Spirulina pyrolysis resulted in higher solid yields compared with Chlamydomonas pyrolysis. The results also showed that Spirulina bio-oil was rich in oxygenated compounds, probably due to its high carbohydrate content, whereas Chlamydomonas bio-oil was rich in nitrogenated compounds because of its higher protein content. The microalgae composition (lipids, protein, carbohydrates) exerted a large influence on the catalytic pathways and led to differences in yield and product distribution. A high percentage of catalysts preferentially promoted a deoxygenation of the bio-oil obtained from Spirulina solar pyrolysis compared with that obtained from Chlamydomonas pyrolysis.  相似文献   

15.
Using Ni/SiC as a catalyst, bagasse was microwave-assisted pyrolysis in a homemade quartz reactor. The results showed that with the continuous increase of Ni content, the experimental catalytic pyrolysis effect on bio-oil became more and more obvious, and the hydrogen yield gradually increased. When Ni content exceeded 8%, the hydrogen yield and bio-oil catalytic pyrolysis efficiency decreased, and the lowest bio-oil yield was 9.55% when Ni content was 15%, With the increase of power, the catalytic cracking efficiency and hydrogen yield of bio-oil increased, With the increase of catalyst dosage, the catalytic efficiency and the hydrogen yield increase gradually. When the catalyst quality exceeds 1/4 of the material, the growth rate of catalytic efficiency decreases, after alkali treatment, the variation law of hydrogen yield and bio-oil is consistent with that without alkali treatment. In contrast, more hydrogen can be produced after alkali treatment. Under the optimum conditions, the hydrogen yield was 35.85 g/kg biomass.  相似文献   

16.
《能源学会志》2020,93(4):1313-1323
In this work, the solar catalytic pyrolysis of Spirulina platensis microalgae using hydrotalcite as a catalyst was studied to improve the yield and quality of the bio-oil obtained from the algae. The effects of biomass loading, reaction time, and catalyst percentage on the product distribution and bio-oil composition were evaluated. The desirability function was used to identify the pyrolysis conditions that maximize the bio-oil yield and its hydrocarbon content. The experimental results indicated that the catalytic pyrolysis of Spirulina platensis produced considerable solid product content, and high liquid yields were reached in some tests favored by the catalyst presence. The hydrotalcite contributed to increasing the hydrocarbon formation in the bio-oil at lower reaction times, demonstrating the great performance of this catalyst for microalgae pyrolysis. At the optimal conditions, a bio-oil yield of 35.94% with 21.71% hydrocarbon content was achieved.  相似文献   

17.
Catalytic pyrolysis is an effective method for converting biomass to value-added chemicals. However, the development of cost-effective catalysts remains a major challenge. In this study, a highly efficient bimetallic Pt–Ni catalyst (Pt to Ni ratio = 0:1, 2:1, 1:1, 1:2, 1:0) was fabricated and used for catalytic biomass pyrolysis upgrading into hydrocarbon-rich bio-oil with pyrolysis-gaschromatography × gaschromatography/mass spectrometry (Py-GC1 GC/MS). The product yield and selectivity of upgraded bio-oil, thermal properties, kinetic and deactivation mechanisms were also determined to investigate the reaction mechanism. It was determined that Pt addition strengthened the NiO and alumina interaction and improved nickel dispersion, promoting CO hydrogenation. Bimetallic catalysts had a higher stability and activity owing to synergistic action of platinum and nickel on γ-Al2O3, and the surface oxygen vacancies were derived from the electron transfer of Pt to Ni and the higher number of super acid-base sites, which inhibited coke deposition. In addition, the higher valence Pt (Pt2+) in the catalyst was favorable for decarboxylation and hydrodecarbonylation reactions. Various metal ratios were employed, and the Pt–Ni/Al = 1:2 catalyst exhibited an excellent catalytic performance, achieving highest peak areas of desired hydrocarbons and aromatic hydrocarbons at 52.67% and 40.25%, respectively, and the lowest peak area of deposited coke at 7.26%, along with a 13.98% weightloss rate.  相似文献   

18.
K modified Ni-based catalysts are used to investigate the effect of in-situ and ex-situ injection of steam (ISI and ESI) on biomass pyrolysis and in-line catalytic steam reforming in a two-stage fixed bed reactor. The results show that 0.5 wt% K is appropriate to modify the Ni-based catalysts for steam reforming of biomass pyrolysis vapor. Compared to the catalytic cracking without steam addition, both ISI and ESI increase the gas yield and the carbon conversion efficiency (Xc) of the pyrolysis vapors. And the ESI is more beneficial to the conversion of pyrolysis vapors to small molecular gases. The maximum hydrogen concentration, hydrogen yield and carbon conversion efficiency (Xc) of staged-gasification can reach 53.8%, 31 mmol/g-bio, and 94.6%, respectively, when both stages are at 700 °C with ex-situ steam injection (S/C = 1.2) and 3 g catalyst loaded in the second stage. Also, the steam is beneficial to removing the depositions of graphitized coke and small molecular polycyclic aromatic hydrocarbon on the catalysts. However, it is yet difficult for steam to react with the highly ordered carbonaceous.  相似文献   

19.
Promising technology for the conversion of cellulose to aromatics by catalytic fast pyrolysis (CFP) was investigated using five zeolite catalysts, i.e., 5A, SAPO-34, HY, BETA and HZSM-5. The relationship between the porosity and acidity of different zeolites with product selectivity was studied. The results showed that both the acidity and pore size of the zeolite significantly affected the production of aromatics and coke, especially the bio-oil composition. The bio-oils obtained over 5A or SAPO-34 (small pore<5.5 nm) have relatively high oxygen content. The BTEXN (benzene, toluene, ethylbenzene, xylenes and naphthalene) carbon yields over weak acidic zeolites of HY and BETA are only 6.5% and 9.0%, respectively. Due to the appropriate pore size distribution and acid position, HZSM-5 gave the highest BTEXN carbon yield of 21.1%. Moreover, the coke deposited on the spent zeolites was analyzed by temperature programmed oxidation. Furthermore, three possible mechanisms that the acid sites catalyze vapor towards non-condensable gases, aromatics and coke were also studied. HZSM-5 achieved satisfactory deoxygenation and aromatic production simultaneously, made it a potential catalyst for producing light aromatics from reforming the biomass pyrolytic vapors.  相似文献   

20.
研究了生物油及其模型化合物在RuNi双金属催化剂作用下加氢脱氧制备烃类液体燃料。实验比较了单金属催化剂与双金属催化剂的反应效果,结果表明双金属催化剂的催化活性更高。在260℃下,RuNi双金属催化剂催化愈创木酚反应,可基本转化为环己烷,而单金属Ru催化剂转化率只有49.4%,单金属Ni催化剂转化率很低。该RuNi双金属催化剂用于生物油的加氢脱氧也有很好的效果,在280℃下,生物油中的碳氢化合物含量从反应前的15.6%增加到反应后的63.0%。  相似文献   

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